Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/m4/stl_hash.m4

Index: third_party/protobuf/m4/stl_hash.m4
diff --git a/third_party/protobuf/m4/stl_hash.m4 b/third_party/protobuf/m4/stl_hash.m4
deleted file mode 100644
index 0722b14a73daa9eddd1b73f1854f1abcfef762b5..0000000000000000000000000000000000000000
--- a/third_party/protobuf/m4/stl_hash.m4
+++ /dev/null
@@ -1,72 +0,0 @@
-# We check two things: where the include file is for
-# unordered_map/hash_map (we prefer the first form), and what
-# namespace unordered/hash_map lives in within that include file.  We
-# include AC_TRY_COMPILE for all the combinations we've seen in the
-# wild.  We define HASH_MAP_H to the location of the header file, and
-# HASH_NAMESPACE to the namespace the class (unordered_map or
-# hash_map) is in.  We define HAVE_UNORDERED_MAP if the class we found
-# is named unordered_map, or leave it undefined if not.
-
-# This also checks if unordered map exists.
-AC_DEFUN([AC_CXX_STL_HASH],
-  [
-   AC_MSG_CHECKING(the location of hash_map)
-   AC_LANG_SAVE
-   AC_LANG_CPLUSPLUS
-   ac_cv_cxx_hash_map=""
-   # First try unordered_map, but not on gcc's before 4.2 -- I've
-   # seen unexplainable unordered_map bugs with -O2 on older gcc's.
-   AC_TRY_COMPILE([#if defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 2))
-                   # error GCC too old for unordered_map
-                   #endif
-                   ],
-                   [/* no program body necessary */],
-                   [stl_hash_old_gcc=no],
-                   [stl_hash_old_gcc=yes])
-   for location in unordered_map tr1/unordered_map; do
-     for namespace in std std::tr1; do
-       if test -z "$ac_cv_cxx_hash_map" -a "$stl_hash_old_gcc" != yes; then
-         # Some older gcc's have a buggy tr1, so test a bit of code.
-         AC_TRY_COMPILE([#include <$location>],
-                        [const ${namespace}::unordered_map<int, int> t;
-                         return t.find(5) == t.end();],
-                        [ac_cv_cxx_hash_map="<$location>";
-                         ac_cv_cxx_hash_namespace="$namespace";
-                         ac_cv_cxx_hash_map_class="unordered_map";])
-       fi
-     done
-   done
-   # Now try hash_map
-   for location in ext/hash_map hash_map; do
-     for namespace in __gnu_cxx "" std stdext; do
-       if test -z "$ac_cv_cxx_hash_map"; then
-         AC_TRY_COMPILE([#include <$location>],
-                        [${namespace}::hash_map<int, int> t],
-                        [ac_cv_cxx_hash_map="<$location>";
-                         ac_cv_cxx_hash_namespace="$namespace";
-                         ac_cv_cxx_hash_map_class="hash_map";])
-       fi
-     done
-   done
-   ac_cv_cxx_hash_set=`echo "$ac_cv_cxx_hash_map" | sed s/map/set/`;
-   ac_cv_cxx_hash_set_class=`echo "$ac_cv_cxx_hash_map_class" | sed s/map/set/`;
-   if test -n "$ac_cv_cxx_hash_map"; then
-      AC_DEFINE(HAVE_HASH_MAP, 1, [define if the compiler has hash_map])
-      AC_DEFINE(HAVE_HASH_SET, 1, [define if the compiler has hash_set])
-      AC_DEFINE_UNQUOTED(HASH_MAP_H,$ac_cv_cxx_hash_map,
-                         [the location of <unordered_map> or <hash_map>])
-      AC_DEFINE_UNQUOTED(HASH_SET_H,$ac_cv_cxx_hash_set,
-                         [the location of <unordered_set> or <hash_set>])
-      AC_DEFINE_UNQUOTED(HASH_NAMESPACE,$ac_cv_cxx_hash_namespace,
-                         [the namespace of hash_map/hash_set])
-      AC_DEFINE_UNQUOTED(HASH_MAP_CLASS,$ac_cv_cxx_hash_map_class,
-                         [the name of <hash_map>])
-      AC_DEFINE_UNQUOTED(HASH_SET_CLASS,$ac_cv_cxx_hash_set_class,
-                         [the name of <hash_set>])
-      AC_MSG_RESULT([$ac_cv_cxx_hash_map])
-   else
-      AC_MSG_RESULT()
-      AC_MSG_WARN([could not find an STL hash_map])
-   fi
-])
-